UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8

Ref: 8P-AR 1595 Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08 

### MAY Z 22014

Honorable Darrell O'Neal Sr., Chairman Northern Arapaho Tribe P.O. Box 396 Ft. Washakie, Wyoming 82514 Dear Chairman O'Neal: The purpose ofthis letter is to provide you with information concerning the U.S. Environmental Protection Agency's designations process for the 2012 primary annual PM2 .5 national ambient air quality standard (NAAQS). Yourtribe may find it important to engage with us in the process ofassigning designations for Indian country. Although your involvement is not required, we would like to invite you to participate in the designations process and to offer you consultation. We wantto ensure transparent and effective communication in developing area designations for the revised PM2 .s NAAQS. Area recommendations for the PM2 .s NAAQS were due to the EPA onDecember 13, 2013; however, the EPA is prepared to accept designation recommendations from tribal leaders until June 13, 2014. On December 13,2013,the EPA revised the PM2.s NAAQS to increase protection ofpublic health from fine particle pollution. The annual PM2 .5 standard was strengthened from 15 11g/m3 to 12 11g/m3• Establishing initial area designations is a key step in the process ofproviding the health and/orwelfare protection intended by the Clean Air Act (CAA). Within two years ofpromulgation ofa new orrevised NAAQS, the EPA must list and designate all areas in the country as either: Attainment

- areas that meet the standard; Nonattainment- areas that eitherdo not meet the standard, or are contributing to a nearby area that does not meetthe standard; or Unclassifiable

- areas where there is insufficient information to make a determination as to attainment. These designations are based on current air quality information, recommendations from state governors and tribal leaders, and otherrelevant information as discussed in the April 2013 designations guidance InitialAreaDesignations for the 2012 RevisedPrimaryAnnualFine ParticleNationalAmbientAir QualityStandard. The guidance is available on the EPA's PM Designations website at http://www.epa.gov/pmdesignations/2012standards/docs/april2013guidance.pdf. Additional information about developing tribal air quality designations is available in the September2013 documentDeveloping Designation Recommendations forAreas of Indian Country, which is available here: http://www.epa.gov/air/tribal/pdfs/DevelopingaDesignationRecommendationforlndianCountry.pdf. We are sending you this letter because your tribe has Treatment in the Same Manner as a State (TAS) status for designations. We will keep you informed as we finalize designations for your tribe's area and invite and encourage you to participate. Please notify us by June 13, 2014, ifyou are interested in consulting with us regarding a recommended designation. When requested, consultationwill beconducted in accordance with the EPA Policy on Consultation andCoordination with Indian Tribes (www.epa.gov/tribal/consultation/consult-policy.htm). We planto formally announce our intended designations for all areas by August 14, 2014. Atthat time we will send another letter to you with our intended designation and offer an additional opportunity to consult with us onthe proposed designation status ofyourtribe's area ofIndian country. In accordance with section 107(d)(l)(B) ofthe CAA, we are required to issue final designations for the 

### PM2.s NAAQS no laterthan December 12, 2014. Our designations will be based onthe most recent three calendaryears ofcertified, quality-assured monitoring data available, and any other relevant information. As the designation process moves forward, we will keep you informed ofany additional guidance or other support activities. We look forward to working with youto develop area designations under the 

### PM2.sNAAQS in a timely manner. Ifyour tribe is interested in consultation orhas questions about the designations process, please do not hesitate to contact me or Crystal Ostigaard ofmy staffat (303) 312-6602 or ostigaard.crystal@epa.gov.

cc: Ryan Ortiz, Environmental Director Jolene Catron, Air Coordinator Sincerely,